This invention relates to a shift control apparatus for an automatic transmission and, more particularly, to a shift control apparatus capable of obtaining an optimum shift timing at the time of a kickdown shift.
Shifting in an automatic transmission is achieved by a combination of engagements of such elements as a one-way clutch, a band brake and multi-plate friction engaging elements, or by a combination of engagements of multi-plate friction engaging elements.
In a shift control apparatus which relies upon the combination of engagements of multi-plate friction engaging elements, a known method of controlling shift shock at the time of a kickdown shift is to slow down, in dependence upon the prevailing vehicle velocity, the rate of a rise in the hydraulic pressure of the engaging elements on the engaging side, which hydraulic pressure rises in conformity with a decline in the hydraulic pressure of the engaging elements on the disengaging side.
An arrangement described in the Toyota Toyace New Car Manual (1984-8), pp. 5-53, can be mentioned as a conventional shift control apparatus which controls shift shock at the time of a kickdown shift using the aforementioned method.